In 1992, a law was passed requiring the release in 25 years of all government documents pertaining to the assassination of President John F. Kennedy. Twenty-five years after 1992 is 2017. Last week, hundreds of boxes of previously secret files with thousands of documents were made public.

They reveal that the CIA had doubts about the findings of the Warren Commission that studied the crime and concluded that Lee Harvey Oswald acted alone in assassinating JFK.

So far, the documents don’t show any questions that Oswald was the killer. But they express the CIA’s concern that important information–specifically, Oswald’s contacts with Soviet and Cuban agents, including a KGB agent with expertise in assassinations–was never fully investigated.

The documents suggest that Oswald had learned about CIA attempts to assassinate Fidel Castro and may have been retaliating against Kennedy.

After the assassination of President John F. Kennedy in November 1963, the CIA appeared eager, even desperate, to embrace the version of events being offered by the FBI, the Secret Service and other parts of the government. The official story: that a delusional misfit and self-proclaimed Marxist named Lee Harvey Oswald killed the president in Dallas with his $21 mail-order rifle and there was no evidence of a conspiracy, foreign or domestic. Certainly, the CIA’s leaders told the Warren Commission, the independent panel that investigated the murder, there was no evidence of a conspiracy that the spy agency could have foiled.

Specifically, key CIA officials were concerned by the mid-1970s that the agency, the FBI, the Secret Service and the White House commission led by Chief Justice Earl Warren had neverfollowed up on important clues about Oswald’s contact with foreign agents, including diplomats and spies for the Communist governments of Cuba and the Soviet Union, who might have been aware of his plans to kill Kennedy and even encouraged the plot. (There is no credible evidence cited in the documents released so far that Cuban leader Fidel Castro or other foreign leaders had any personal role in ordering Kennedy’s murder.)

The CIA documents also offer tantalizing speculation about the chain of events in late 1963 that explained Oswald’s motives for killing Kennedy, which have previously never been established with certainty—how he may have become enraged after reading a detailed article in his hometown newspaper in New Orleans in September suggesting that his hero Castro had been targeted for assassination by the Kennedy administration. According to that theory, Oswald, who had rifle training in the Marine Corps, then set out to seek vengeance on Castro’s behalf—to kill Kennedy before the American president managed to kill the Cuban leader.

If that proved true, it would have raised a terrible question for the CIA: Was it possible that JFK’s assassination was, directly or indirectly, blowback for the spy agency’s plots to kill Castro? It would eventually be acknowledged the CIA had, in fact, repeatedly tried to assassinate Castro, sometimes in collusion with the Mafia, throughout Kennedy’s presidency. The CIA’s arsenal of weapons against Castro included a fungus-infected scuba suit, a poison-filled hypodermic needle hidden in a pen—and even an exploding cigar. The Warren Commission, never told about the CIA’s Castro plots, mostly ducked the question of Oswald’s motives, other than saying in its final report that he had expressed a “hatred for American society.”

JFK historians and the nation’s large army of private assassination researchers are still scrambling to make sense of the latest batch of tens of thousands of pages of previously secret CIA and FBI documents that were unsealed last week by the National Archives. The documents—441 files that had previously been withheld entirely, along with 3,369 other documents that had been previously released only in part—were made public under terms of a 1992 law that requires the unsealing of all JFK assassination-related documents by October, the law’s 25-year deadline.